This request is for funds to purchase a JEOL 1011 transmission electron microscope equipped with a digital camera. This instrument will be housed within the Center for Biologic Imaging (CBI) at the University of Pittsburgh School of Medicine. The mandate of this core facility is to provide access to a full range of light and electron optical, image analysis, and morphometric methods to all research groups within the University of Pittsburgh School of Medicine. Electron microscopy is an essential service provided by the center, the current core use electron microscope within the facility is a JEOL 100CX, which is more than 20 years old. Until the spring of last year his microscope has provided reliable high quality EM time to the PHS funded research base within the University. Unfortunately a catastrophic water failure (detailed within the body of the grant) severely damaged the microscope such that it is very difficult to keep it running at all. This failure was particularly untimely as the use of EM within the center has continued to grow such that we are no longer able to satisfy user needs even with a stable instrument. Therefore, the reasons for this application are to: 1: Provide critically needed instrument time; 2: Replace the 100CX instrument which is no longer serviceable as a core microscope; 3: Provide digital image collection technologies, not available with the current microscopes in the center but commonly requested by users. Since the CBI commenced operations 11 years ago, it has become an integral part of the medical research community currently participating in research projects with more than 80 PHS funded groups within the medical area, as well as in PHS supported projects with investigators at institutions around the country. As the PHS funded user base continues to expand, a lack of available EM time has become a major limiting factor in the utility of the center; this leads to considerable frustration amongst users. The acquisition of the requested instrument will allow individual users more ready access to transmission electron microscopy such that the current user bottleneck for the current instrument will be resolved.